Thermo-magnetic contact device



OC- 9, 1962 c HUETTEN 3,057,978

THERMO-MAGNETIC CONTACT DEVICE:

Filed Oct. 24, 1960 United States Patent Olllice 3,057,978 Patented Oct. 9, 1962 3,057,978 THERMO-MAGNETIC CONTACT DEVICE Clarence Huetten, Indianapolis, Ind., assignor to P. R. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Filed Oct. 24, 1969, Ser. No. 64,545 3 Claims. (Cl. 20D-88) The present invention relates to devices for intermittently varying electrical currents generally known as flashers and has particular reference to such devices incorporating thermo-magnetic contacts.

An object of the present invention is to provide an electrically operable flasher circuit and switching mechanisrn in which a flasher periodically alters the current supplied to a lamp or other signa-l devices so that the lamp or device may be caused to llash or operate periodically.

Prior periodic or flasher switches were of the mechanical or electromechanical variety requiring a great many moving parts and complicated construction tending to increase the cost in `order to obtain reliability.

It is therefore an object of the invention to provide a flasher switch which is compact in construction, inexpensive to manufacture, si-mple of installation and particularly adapted for controlling the turn signals and pilot lights of an auto turn signal system.

It is also an object of the invention to provide an electric current interrupter in which the contacts per se, are important in determining the flashing frequency of the device.

The foregoing and other objects are `attained in the embodiment of the invention shown in the drawings, in which FIG. l represents an embodiment of the flasher invention constructed in a manner such that a permanent magnet contact is used in conjunction with a contact fabricated from a magnetic material whose permeability changes as a function of temperature, and

FG. 2 is a diagram of the electrical circuit `of the flasher of the present invention.

Generally speaking, many magnetic materials exhibit a decrease in permeability when heated. The present invention describes a closed electrical circuit utilizing a permanent magnet as one contact, and as a second contact, a magnet material exhibiting a decrease in permeability when heated. The latter contact can open and close the electrical circuit by being heated with the passage of an electrical current therethrough. The characteristic of the circuit is variable, as desired, by altering the permeability range of the contact to a point where its permeability is reduced to allow a bias spring to pull magnetic contact having variable permanence away from a permanent magnet so as to determine the flashing frequency of the circuit.

Referring now to the figures `of the drawing, FIG. 1 represents the flasher embodiment in which three contacts are used; a permanent magnet contact, a magnetic contact of variable permanence and a non-magnetic contact. The llasher comprises a base on which a pair of contact assemblies 11 and 12 are placed in cut-out forms 13 and 14 in the base. Each contact assembly comprises a terminal section 15 integrally joined to a collar or staking tab section 16. To the tab section there is placed an offset portion 17 horizontally extending therefrom. A permanent magnet contact 18 held on a contact spring 19 is joined to one of the assemblies, while a magnetic contact 2t) is connected to the other assembly. Above the magnetic contact 20 is placed a non-magnetic contact 21 held on a llash rate adjustment arm 22 integrally joined to the magnetic contact arm 23 by means of a vertically extending section 24. When fitted together the permanent magnet contact mates with the magnetic contact and is situated between it and the non-magnetic contact.

In FIG. 2, there is shown the flasher circuit illustrated in the embodiment of FIG. 1 and the mode of operation thereof. A lamp load 30 of 4 amperes and a voltage source of l2 volts D C. is used. In the oil or hold position, the permanent magnetic contact is attracted to the magnetic contact. This magnetic contact is fabricated of a material so that its resistance and thermal mass is controlled in such a way that a current through the contact pair will heat the magnetic contact material to a temperaure which reduces its permeability to a point to allow a bias spring 31 to pull the magnetic contact away from its associated permanent magnet.

Thus when switch 32 is closed, current ilo-ws through the circuit and the magnetic contact begins to heat up due to its resistance. The lamp at this point will not glow due to the high voltage drop across the magnetic contact in series with the lamp. When the magnetic contact heats up an amount sufficiently to decrease its permeability, the bias spring flips the permanent magnet contact over to the non-magnetic contact. In this position the light glows and the magnetic contact begins to cool. As soon as the magnetic contact cools an a-mount sufficient to increase its permeability, the premanent magnet contact again is attracted to and is llipped over to the magnetic contact. The cycle is repeated While the switch is closed. The magnetic contact during the operation had a resistance of approximately 5 ohms. The resistance was obtained for the contact by mixing a nickel-iron powder with a ferrite powder, pressing and sintering the compact. If necessary, to alter the frequency of operation, the construction as shown in FlG. 1 utilizes an adjustment arm 22 for varying the contact spacing between the non-magnetic contact and the magnetic contact.

It is apparent, therefore, that the construction as described allows for an exceedingly simple, sturdy and reliable flasher. Moreover the principle of utilizing a magnetic contact operation wherein the current flow allows for a decrease in 4magnetic permanence for controlling switching operations is adaptable to many other devices and accordingly it is intended that other modifications and certain changes in design and construction may be resorted to from time to time by persons versed in the art, without departing from the spirit and intent of the invention or the scope of the appended claims.

What is claimed is:

1. A flasher comprising an electrical circuit connected to a power source and to a load, said circuit including a permanent magnet contact, a magnetic contact of varying permeability, said permeability being varied by the heat generated in the current passing therethrough, said permanent magnet contact being placed on a bias spring adjacent said magnetic contact and a non-magnetic contact placed adjacent and above said magnetic contact of varying permeability, said magnetic contact being moved alternately against said permanent magnetic contact and said non-magnetic Contact upon the ilow of electric current through said magnetic contact so as to heat the same to vary the permeability thereof whereby said load is intermittently affected.

2. A flasher comprising an electrical circuit connected to a power source and to a load, said circuit including a permanent magnet contact, a magnetic contact `of varying permeability, said permeability being varied by the heat generated in the current passing therethrough, said permanent magnet contact being placed on a flexible spring holder, a non-magnetic contact connected to said load, said magnetic contact connected to said load in parallel therewith and being moved alternately between said permanent magnet Contact and said non-magnetic contact when current passes therethrough to vary its permeability.

3. A signal flasher comprising an electrical circuit connected to a direct current power source and to a load, said Y circuit including a permanent magnet contact, a thermo magnetic contact of varying permeability, said permeability being varied by heat generated by current passing therethrough, said permanent magnet being placed on a bias spring, a non-magnetic contact connected to said load, said magnetic contact connected to sai-d load in parallel therewith, means for adjusting the spring between said magnetic and non-magnetic contact to vary the fre quency of movement between said latter contacts when current passes through said ymagnetic `contact to vary its permeability and whereby said load frequency is varied accordingly.

References Cited in the le of this patent UNITED STATES PATENTS Lacey July 18, 1939 Klapperich Sept. 17, 1940 Newell Ian. 6, 1942 Ulanet Mar. 9, 1948 Graham Dec. 22, 1953 Johnston Sept. 20, 1955 Keen June 19, 1956 Simmons NOV. 14, 1.961

FOREIGN PATENTS France Feb. 26, 1945 Great Britain Apr. 5, 1948 

